286 Cellulose 



(carbonate and silicate of soda), (b) bleaching with calcium 

 hypochlorite solution in a closed vessel (Mason Kier) ; after 

 which the cloth was washed, ' soured ' in weak acid, washed up, 

 and dried. The printing processes were those ordinarily employed 

 for cotton goods, the colours being developed and fixed by the 

 usual process of steaming, in an atmosphere of dry stream at 

 4 Ib. (per square inch) pressure. It was in the latter case that the 

 discolouration and tendering effect chiefly showed themselves. 

 The cause being traced, the remedy was easily devised, the 

 process being modified as follows : (a) in the bleaching 

 process, sodium hypochlorite was substituted for the lime 

 compound and in this way the chlorination of the fibre-sub- 

 stance was arrested ; (b) as a last treatment, after souring and 

 washing, the goods were run through a solution of sodium 

 bisulphite (i p.ct. SO 2 ), and dried after squeezing. In this 

 way a residue of the normal sulphite (Na 2 SO 3 ) was left in the 

 cloth, and this was found to prevent discolouration in the 

 steaming process. 



In this method of bleaching, the loss of weight of the fabric 

 was from 8-12 p.ct, the colour obtained being the pale 

 cream shade of the highly purified lignocellulose. The results 

 obtained by bleaching with permanganates are superior to those 

 with the hypochlorites, but at much greater cost. The process 

 is therefore but little used industrially. 



(2) Linen yarn and doth: partial bleach. In the linen 

 industry, in addition to the full bleaching of shirtings, sheetings, 

 cambrics, &c., there is a large practice in partial bleaching of 

 various grades. These processes are familiarly designated as 

 * whitewashing,' in contradistinction to the * bottom bleaching' : 

 in the former the non-cellulose constituents are only partially 

 removed, and the residues whitened by bleaching agents ; in 

 the latter they are entirely eliminated, leaving the residue of 

 pure flax cellulose. The partial bleaches in question are 



